The present invention is directed to an optical transmission element comprising at least one light waveguide that is received in the interior of a two-layer outside sheath, wherein a soft, oil-containing compound is provided between the outside sheath and the light waveguide.
U.S. Pat. No. 4,641,916, whose disclosure is incorporated herein by reference thereto, and European Patent Application 0 151 743 disclose optical transmission elements wherein the optical waveguide is introduced in a two-layer outside sheath and there is a soft oil-containing filling compound provided between the outside sheath and the light waveguide. In these disclosures, it proceeds on the presumption that the harmful influence of the oil constituents of the soft filling compound are optimally suppressed to a far-reaching degree in that the material of an inside layer of the two-layer outside sheath is composed of aramides, polyethersulfones or polycarbonates. Although these materials are largely resistant to swelling agents, particularly resistant to hydrocarbon oils of the filling compounds, they have the disadvantage that they are extremely sensitive to stress cracks. In order to counter this disadvantage, a protective layer composed of a polyester, particularly of a polybutylene terephthalate is applied onto the outside of the inside layer, which is composed of either a polyethersulfone or a polycarbonate.